| 摘要 |
A pipe-in-pipe assembly 46 comprises thermally-insulating spacers positioned in an annulus (16, Fig 8) to act radially between inner 12 and outer 18 pipes. The spacers comprise at least one circumferentially-extending array of circumferentially-spaced ribs 26 that define longitudinally-extending passageways in gaps 28 between neighbouring ribs of the array. Cables 10, which may include heating elements, extend longitudinally along the annulus outside the inner pipe. The cables extend longitudinally along the passageways. At least one insulation layer 48 and 52 is disposed radially outboard of the cables and this layer may comprise insulating elements 48 disposed in the gaps between the ribs and/or an insulating layer 52 extending around the inner pipe, positioned radially outboard of the ribs and bridging the gaps. Bands 34 may encircle and retain components of the insulation layer. Insulation (52 and 62, Fig 14) may also be disposed on the inner pipe between first and second arrays of ribs, those arrays being spaced longitudinally from each other. |
